#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<math.h>
int main()
{
	double a, b, c, s, area;
	a = 3.67;
	b = 5.43;
	c = 6.21;
	s = (a + b + c) / 2;
	area = sqrt(s * (s - a) * (s - b) * (s - c));
	printf("a=%f\t b=%f\t c=%f\n", a, b, c);
	printf("area=%f\n", area);
	return 0;
}